【Abstract】 Objective To investigate the effects of EGCG on keratin 17 (K17)mediated human keratinocyte apoptosis. Methods Different concentrations of EGCG were treated with HPV11.HaCaT for 12 h. The expression of K17 was tested by qRTPCR and Western blot. Flow cytometry (Annexin VFITC and PI double staining) was used to study the apoptosis rates of KC, HaCaT and HPV11.HaCaT cells. The expression levels of K17 and Caspase 3 in pathological sections of patients with psoriasis and condyloma acuminatum were tested by immunohistochemistry and Western blot method. Construction of K17 overexpression vectors (pcDNA31（+）/K17), and the vectors were transfected in KC and HaCaT for 48 h, and further EGCG（50 mg/L）was treated the cells for 12 h. The level of K17 and apoptosis were detected. Results The expression of K17 was significantly decreased in KC, HaCaT and HPV11.HaCaT (P＜005) by EGCG treatment at 12 h with a concentration dependent trend. The positive rate of K17 in psoriasis and condyloma acuminatum was increased, but the positive rate of Caspase3 was decreased. However, the expression of CleavedCaspase 3 was significantly downregulated (P＜005). EGCG (50 mg/L ) increased the apoptosis rate of KC, HaCaT and HPV11.HaCaT (P＜001). EGCG attenuated the role of pcDNA3. 1（+）/K17 on cell apoptosis of KC and HaCaT (P＜001).Conclusion EGCG promotes keratinocyte apoptosis by inhibiting K17, which provides a basis for the basic research and clinical treatment of psoriasis and condyloma acuminatum.